Ultra high frequency tube



Patented Dec. 28, 1948 ULTRA HIGH FREQUENCY TUBE Nathaniel Rochester, South Hamilton, Mass., as-

signor to Sylvania Electric Products Inc., Salem, Mass., a corporation of Massachusetts Application December 18, 1944, Serial No. 568,734

1 Claim. 1

This invention relates to tubes for ultra high frequency, and in particular to oscillators and amplifiers for the microwave region.

An object of the invention is to produce a tube of the velocity modulated type for microwaves and particularly to produce such a tube for use as a beating oscillator in a heterodyne receiving set.

Figure 1 is a sectional profile view of a tube according to the invention;

Figure 2 is a sectional profile view of another tube according to the invention; and

Figure 3 is a plan View of a portion of the waveguide in the tube of Figure 2.

My invention is also useful as a transmitter tube for communications, and for other purposes.

A feature of the invention is the use of a magnetic field to analyze a velocity modulated beam of electrons in order to obtain an amplitude modulated beam of electrons.

Other objects, advantages, and features of the invention will be apparent in the following specication taken. in connection with the accom panying drawings in which:

In Figure l the glass envelope i has a waveguide 2 sealed through it at one end and is electrically coupled to a waveguide resonator chamber l0, by means of another piece i6 of waveguide whose dimensions are such as to give the proper electrical coupling. 'Ihe tube also contains a cathode 1 which is heated by some suitable means, such as the lament 4 shown in the figure. The cathode is made negative with respect to the resonator I9, so electrons which are emitted by the cathode 1 are accelerated toward the resonator I0. These electrons are formed into a beam in the usual manner by means of the focussing ring 8, so that they pass through the rst set of holes 9, in the resonator IU. An oscillating electric field exists in the resonator. Consequently the electron beam is velocity modulated during its first passage through the resonator l0. After pasing through the resonator, the electron beam enters a magnetic eld represented in the usual manner by the crosses I1, which represent lines of form extending from a conventional magnetic poll 24. This magnetic field causes the electron beam I8 to follow a roughly semicircular path, back to the second set oi holes 5 in the resonator. The faster electrons will travel in a larger circle i9 than the slower electrons, so when the electron beam again reaches the resonator, only the faster, or only the slower, depending on the adjustment of the magnetic eld, electrons pass through the second set of holes 5. Therefore, the beam which passes through the resonator will be amplitude modulated and so deliver energy to the resonator I0. The exact phasing of the velocity modulation with the reentering beam is accomplished by a line adjustment of the magnetic eld which does not appreciably aiect the fo- 2 cussing action. Part of the energy which is delivered to the oscillating field maintains the field in the resonator, and part passes through the coupling I6, into the output waveguide 2, and out of the tube to be used. A collector electrode i4 is provided to remove the spent electrons. Lead-in wire 23 extends from focusing ring 8 through glass envelope l.

In order to allow more current in the electron beam, it .may be convenient to use several holes 9, I2, I3, i5 in parallel, and also 5, vfi, 2l, 22 at the other end, as shown in Figures 2 and 3. One advantage of using a large current is that more energy is delivered to the resonator and hence the power output can. be larger. In order to obtain a still further increase in the power output, it may be convenient to have more resonator chambers l0, Il as shown in Figure 2. One advantage of a larger number of resonators I0 is that there would be an increase in the available power output.

In either case, the coupling I6 should be loose enough so that the resonant frequency will be determined by resonator l0, and ll if so used.

For best results, the velocity of the electrons passing through the waveguide i0 and the distance of their path through the waveguide l0 at this point should be chosen so that this distance is equal to an odd number of half-periods at the desired wavelength. The tuning will be better if the odd number is small.

What I claim is:

An ultra-high frequency oscillator comprising: a longitudinal waveguide closed at one end and open at the other for transmission of power therefrom and having two spaced apart sets of openings therein for the passage ci electron beams laterally therethrough at two separated places therein, a cathode in register with one set of openings, means on the opposite side of said waveguide from said cathode for producing a magnetic iield on said opposite side of said waveguide from said cathode and transverse to the path of the electron beam through said sets of openings an-d a collector electrode on the same side of the waveguide as the cathode and in register with the second set of openings in the waveguide. l

NATHANIE-L ROCHESTER.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Number Name Date 2,260,041 Mahl et al Oct. 21, 1941 2,272,165 Varian et a1. Feb. 3, 1942 2,281,935 Hansen et al. May 5, 1942 2,399,325 Co-ndon Apr. 30, -1946 2,409,179 Anderson Oct. 15, 1946 2,415,749 Malter Feb. l1, 1947 

